The pensioner was punched to the face, which knocked him to the floor, and while down Taylor kicked him to the ribs and head.

“He was still on the floor when a neighbour shouted to leave him alone,” said Ms Knight.

The court heard the victim’s wife, Jocelyn, 70, would now not allow him to answer the door at night and was frightened of further problems with Taylor.

Ms Knight said Mr McKenzie, who suffers with diabetes and a heart condition, was still experiencing blurred vision and difficulties in putting in his hearing aid.

“He served in the armed forces for 40 years and nobody has ever lifted a finger against him before,” said Ms Knight.

The court heard Taylor has 22 court appearances for 44 offences during a 32-year criminal career, including common assault, five for criminal damage, four for assault occasioning actual bodily harm and two for causing grievous bodily harm.

Andrew Davies, defending, said: “He is distraught and ashamed that he has acted in such a fashion.”

Urging the court to impose a suspended sentence because of the “significant impact” it would have on his life, he said Taylor, who has an eight-year-old son, had been drinking heavily since the breakdown of his relationship 18 months ago and had been using mephedrone, commonly known as meow meow.

Jailing Taylor for 12 months Judge John Curran told him the assault had led to a serious loss of confidence for the McKenzies and added: “This was a dreadful assault on an elderly and vulnerable man.”